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Cranial Nerves 1 2 3 4 5 6 7 8 9 10 11 12 Olfactory Optic Ocularmotor Trochlear Trigeminal Abducent Facial Vestibulocochlear Glossopharyngeal Vagus Accessory Hypoglossal Functional Components Somatic Motor Branchial Motor Visceral Motor Visceral Sensory General Sensory Special Sensory General somatic efferent, not from embryonic pharyngeal (branchial) arches Ocular muscles, tongue Special Visceral efferent, muscles of mastication from embryonic pharyngeal (branchial) arches General visceral efferent, cranial parasympathetic system General visceral afferent, convery sensory info that does not normally reach consciousness (from parotid, carotid body and sinus, middle ear, pharynx, larynx, trachea, bronchi, lungs, heart, esophagus, stomach, SI) General somatic afferent, general sensation from skin, mucous membranes Special visceral afferent, taste, smell, vision, hearing, balance General Clinical Recovery *Severely injured cranial nerves do not regenerate Partial/complete recovery may occur following traumatic injuries, except CN I, II (which are tracts) Jugular Foramen Syndrome multiple cranial nerve palsies (often tumor)-CN IX, CN X, CN XI Trigeminal neuralgia disorder of sensory division of trigeminal nerve, idiopathic, paroxysms of sudden stabbing pain, maxillary nerve distribution is most common Cranial Nerve Courses and Cranial Exits Nerve Cranial Exit Nerve Cell Bodies Olfactory CN I Optic CN II Foramina in cribiform plate Optic Canal Olfactory epithelium (olfactory cells) Retina (ganglion cells) Oculomotor CN III Superior Orbital Fissure Midbrain, ciliary ganglion Trochlear CN IV Superior Orbital Fissure Midbrain Trigeminal Ganglion Mandibular CN V3 Superior Orbital Fissure Foramen Rotundum Foramen Ovale Abducens CN VI Superior Orbital Fissure Facial CN VII Temporal Zygomatic Buccal Mandibular Cervical Vestibulocochlear CN VIII Internal acoustic meatus, facial canal, stylomastoid foramen Pons, geniculate ganglion Internal acoustic meatus Vestibular ganglion, spiral ganglion Glossopharyngeal CN IX Jugular Foramen Medulla Otic ganglion, superior, if ganglion Vagus CN X Jugular Foramen Medulla, superior, if ganglion Accessory CN XI Cranial Root Spinal Root Jugular Foramen Hypoglossal CN XII Hypoglossal Canal Trigeminal CN V Opthalmic CN V1 Maxillary CN V2 Trigeminal Ganglion Pons/Trigeminal Ganglion Pons Medulla Spinal cord Medulla Course Through foramina, pierce dura, arachnoid, olfactory bulb (synapse w/ mitral cells) Retinal ganglion cells, pierce scleraorbitoptic canalforms optic chiasm (partial crossing)optic tractlateral geniculate bodies of thalamus Midbrainpierces duraruns in lateral wall of cavernous sinussuperior orbital fissureorbitsplits SuperiorS Rectus, Levator p. s. Inferiorinf, med rectus, inf obliq., parasym. fibers to cilliary muscle, sphincter pupillae Periaqueductal grey matterdorsal surface of midbrainwraps around brainstempierces duralateral wall of cavernous sinussuperior orbital fissuresuperior oblique Only cranial nerve to emerge dorsally from brainstem Pons via small motor root, large sensory root Sensory rootsup orbital fissureupper eyelid, up, plus bridge of nose to nostril Sensory rootforamen rotundumlower eye to upper lip Sensory/Motor rootforamen ovalelower jaw, muscles of mastication, floor of oral cavity Ponsemerges b/t pons, medullapontine cistern, runs along basilary a.pierces durain SAS, bends over petrous part of temporal bone enters cavernous sinussup orb fissurelateral rectus junction of pons/medullaposterior cranial fossainternal acoustic meatusfacial canal (temporal bone) (geniculate ganglion)stylomastoid foramenparotid (parotid plexus)terminal branches Junction of pons/medullainternal acoustic meatussplits Vestibularvestibular ganglion, semicircular ducts Cochlearspiral ganglionlabyrinthine artery Medullajugular foramen (superior/inf ganglia)b/t superior, middle constrictor muscles of pharynxoropharynx, tongue Parasympatheticotic ganglion Rootlets from medullajugular foramen (superior/inf ganglia)carotid sheath to root of neckthorax (heart, lungs)join at esophageal plexus (vagi+symp trunks) w/esophagus through diaphragm to abdomenant/post vagal trunks (eso, stom, GI tract) Cranial-rootlets in medulla, spinal-rootlets in C1C5join at jugular foramenseparatecranial root joins vagus, spinal rootICApenetrates SCMposterior border of SCMsuperior border of trapezius Rootlets of medullahypo. canalcervical plexusinf. to angle of mandiblecurves anteriorly, enters tongue Cranial Nerve Function Nerve Olfactory CN I Optic CN II Oculomotor CN III Trochlear CN IV Trigeminal CN V Opthalmic CN V1 Motor Vision Extraocular muscles, upper eyelid Parasympathetic: Constriction of pupil, ciliary muscles of lens (accommodation of lens) Superior oblique, turn eye inferolaterally General somatic afferent: scalp, upper part of face, deep face, upper eyelid General somatic afferent: middle part of face and deep face Maxillary CN V2 Mandibular CN V3 Special visceral efferent (branchial motor) Muscles of mastication, tensor tympani Abducens CN VI Facial CN VII Temporal Zygomatic Buccal Mandibular Cervical Lateral rectus, turn eye laterally Motor to muscles of facial expression, scalp, stylohoid, posterior belly of diagastic Taste-anterior 2/3 tongue, palate, floor of mouth Sensory-external acoustic meatus Hearing Equilibrium Stylopharyngeus-swallowing Parasympathetic: parotid Vagus CN X General somatic afferent: lower part of face, jaw, oral part of tongue, oral cavity floor Parasympathetic: submandibular, sublingual, lacrimal glands, glands of nose, palate Vestibulocochlear CN VIII Glossopharyngeal CN IX Sensory Smell Motor to constrictor muscles of soft palate, pharynx, laryngeal, palatoglossus, sup.2/3 esophagus Taste-posterior 1/3 Sensation-external ear Visceral sensation-parotid, carotid body, sinuses, pharynx, middle ear Visceral sensation-inf. pharynx, larynx, thoracic, abd. organs Taste: epiglottis, palate Parasympathetic: trachea, bronchi, heart, eso., stomach, intestine Accessory CN XI Cranial Root Spinal Root Hypoglossal CN XII Motor to soft palate, pharynx (cranial root) SCM, trapezius (spinal root) Motor to intrinsic muscles of tongue and all “glossus” except palatoglossus Sensory-auricle, dura mater of posterior cranial fossa Cranial Nerve Tests and Pathology Nerve Function Test Pathology Olfactory CN I Smell Identify Odors Anosmia (loss of smell)-aging, affects taste; may be clue to fracture and CSF rhinnorea, may be caused by tumor Olfactory Hallucinations-imaginary odors, involuntary movements of lips, tounge Optic CN II Vision Gross Vision Visual Fields Opthamoscope Papilledema (edema of optic disc) –incr. CSF pressure on SAS, (indicator of ICP, useful before lumbar puncture) Optic Neurosis-diminution of visual acuity-optic disc appears smaller (inflammatory, degenerative, toxic, etc) Visual Field Defects –tumors of pituitary, berry aneurysm of ICA or ant. cerebral a.; Oculomotor CN III Move Eye Constrict Pupil Eye Movements Pupillary Reflex Complete Lesion Signs: Ptosis – drooping of eyelids No papillary reflex Dilation of pupil – (dilator muscle unopposed) Eye abducted – “down and out” No accommodation of lens Compression- 1st sign is slowness of papillary response Trochlear CN IV Superior Oblique Turn eye inferiomedially Diplopia (double vision) when looking down Trigeminal CN V Opthalmic CN V1 Maxillary CN V2 Mandibular CN V3 Sensation of Face Muscles of Mastication Equal sensation on sides of face Muscle tone when bite down Corneal reflex Injury: trauma, aneurysm, meningeal infections Paralysis of muscles of mastication, deviation of lower jaw to affected side Loss of sensation of face Loss of corneal reflex, sneezing reflex Trigeminal neuralgia Abducens CN VI Abduct eye (lateral rectus) Eye movements Often stretched w/ high ICP (long course) Aneurysm of circle of willis, tumor, pressure from artherosclerotic ICA in cavernous sinus Medial deviation of affected eye Facial CN VII Temporal Zygomatic Buccal Mandibular Cervical Taste (ant 2/3) Facial expression Identify Taste Make Faces Most frequently paralyzed Trauma, fracture of temporal bone, aneurysms, meningeal infections Bell’s palsy Parotid laceration/contusion:paralysis of facial muscles but forehead does not wrinkle Fracture of temporal bone: facial mus paralysis, dry cornea, loss of taste Intracranial hematoma (stroke): forehead wrinkles, paralysis of contralateral facial mus Vestibulocochlear CN VIII Hearing Equilibrium Hear sound in each ear, balance, walk in straight line Acoustic neuroma (tumor of nerve): unilateral hearing loss, tinnitus (noises in ear) Vertigo-often w/ headache, nausea after traumaperipheral vestibular nerve lesion Glossopharyngeal CN IX Taste Swallowing Gag reflex Stick out tongue, ahh Gag reflex absent on side of lesion Loss of taster to posterior 1/3 Vagus CN X Pharynx, palate, larynx, visceral Stick out tongue, ahh Voice change, uvula Deviation of uvula to normal side Dyspagia-difficulty swallowing sensation from respiratory sys, aortic body, GI tract Voice weak, tires easily-lesion to superior laryngeal nerve Dysphonia-difficulty speaking-injury to recurrent laryngeal n. Inspiratory stridor, aphonia (loss of voice)paralysis of both recurrent laryn. Nerves Accessory CN XI Cranial Root Spinal Root Soft palate, pharynx, SCM, Trapezius Turn head against resistance, raise shoulder on each side Weakness of SCM, trapezius Drooping of shoulder (Neck laceration) Hypoglossal CN XII Tongue muscles Stick tongue straight out Tongue deviation to affected side (neck laceration, basal skull fracture)
